How?Add the shio kombu to the leftover brown rice and gently heat them up. Fold the rice a few times so the shio kombu can fully mixed together with the grains.Drain out any excess oil or water from the canned tuna. Transfer about 2 to 3 tablespoons of tuna to a bowl and mix with 1 tablespoon of Japanese mayo.Take one sheet of dried seaweed (nori) and cut with a sharp knife to two smaller rectangular sheets. You can also find small rectangular shaped dried nori as snacks at Asian grocery store, which work just as well but can be on the smaller side for the rice balls.Sprinkle some salt to drinkable water and stir till dissolved.Wet both palms with salted water before making the rice balls. It helps in preventing the grains from sticking on hands. Take one scoop of rice and gently flatten the grams on one palm. Add about one tablespoon of the tuna mayo mixture to the center. Top the tuna mayo with more rice and start forming all these ingredients into a rice ball.

It takes a few practice to perfect the triangular shaped onigiri, but a simple round one works just as well as long as the filling does not pop out in between the grains.

Wrap the rice balls with nori sheets right before serving.

Tuna can be substituted with grilled salmon or canned flaky salmon sold in Japanese grocery store.